The present application relates to a textile fabric having a water-repellent finish and to a method for producing the same.
Textile fabrics having water-repellent finishes are known.
The patent specification U.S. Pat. No. 3,480,579 describes a solid water-repellent composition comprising                (a) a melamine derivative wherein all 6 H atoms of the three NH2 groups are substituted by                    (CH2OR)x and (CH2O2CR1)y, wherein            R is a C1-C6 alkyl group,            R1 is an aliphatic hydrocarbon group having 11-23 C atoms,            y is an integer from 2 to 5 and            x+y=6,                        (b) a wax, and        (c) a surfactant of the formula R2N(R3)2.HO2CR4, wherein                    R2 is a C12-C18 alkyl group,            R3 is a C1-C4 alkyl group, and            R4CO2H is a carboxylic acid having at least 1 C atom,            and wherein the salt R2N(R3)2.HO2CR4 contains not more than 25 C atoms.                        
The patent specification DE 870 544 describes a method for producing a water-repellent finish on fiber materials wherein the fiber materials are treated with solutions of derivatives of methylol amino triazines containing at least one aliphatic residue with 4 C atoms and of other hydrophobic compounds, such as paraffin, waxes such as beeswax, or fatty substances, e.g., esters of fatty acids with a higher molecular weight, such as montanic acid, in organic solvents if necessary, with addition of acidic or acid evolving catalysts, and after removing the solvent if applicable, said treated fiber material is subjected to a heat treatment, preferably at 125 to 150° C.
The term “paraffin”, according to “RÖMPP CHEMIE LEXIKON”, 9th ed., vol. 4 (1991), page 3216, refers to a solid, semisolid or liquid mixture of refined, saturated, aliphatic hydrocarbons. A solid paraffin wax is hard paraffin, a solid crystalline mass having a solidification point of 50-62° C. on the rotating thermometer. For semisolid paraffinic grades having a melting point of 45-65° C., designations such as soft paraffin wax are known, and for those having a melting point of 38-60° C., designations such as petroleum jelly are known. The liquid paraffin forms are often classified as mineral oils in the industrial field and together are called paraffin oil or white oil. Some paraffin fractions are treated as waxes.
The term “wax”, according to “RÖMPP CHEMIE LEXIKON”, 9th ed., vol. 6 (1992), page 4972, refers to substances that usually exhibit, inter alia, the following properties: kneadability at 20° C., firm to brittle hardness, coarse to fine crystallinity, and melting above 40° C. without degradation. According to “RÖMPP CHEMIE LEXIKON”, 9th ed., vol. 1 (1989), page 412, beeswax is a wax obtained from the honeycombs of bees and having a melting point of 61-68° C. Beeswax consists of cerin, a mixture of cerotic acid (hexacosanic acid; C25H51—COOH; melting point=88° C.) and melissic acid (tricotanoic acid; H3C—(CH2)28—COOH; melting point=93.4-94° C.) and of an ester blend called myricin containing about 70 esters of C16 to C36 acids and C24 to C36 alcohols.
The term “fatty substances” refers to “fats” that consist, according to “RÖMPP CHEMIE LEXIKON”, 9th ed., vol. (1990), page 1339, essentially of mixed glycerol esters of higher fatty acids. Montanic acid (H3C—(CH2)26—COOH) has a melting point of 78° C. Hence, esters of montanic acid with higher fatty acids have a melting point above 78° C.
The examined and published patent application DE 1 017 133 describes a method for making fiber materials water-repellent by                i) impregnating the fiber materials in an impregnation bath, wherein the impregnation bath comprises an aqueous emulsion comprising                    10 parts paraffin per 10 parts of a condensation product of a highly etherified methylol melamine methyl ether esterified with 2 moles of stearic acid and of stearic acid diglyceride, and moreover            18 parts of the acetate of the ternary basic condensation product of a highly etherified methylol melamine methyl ether, stearic acid and triethanolamine, as                            well as small amounts of a curing catalyst,                                                ii) drying of the impregnated fiber materials, and        iii) curing of the condensation products in a conventional manner, i.e., by a thermal treatment, e.g., at 120 to 150° C. for 5 to 15 minutes.        
Especially textile fabrics of aramid fibers intended for use in ballistic applications require a water-repellent finish in order to achieve the required protective effect, expressed by the v50 value. It is known to use finishes for this purpose that contain acrylate polymers with perfluoroalkyl groups having the structure CF3—(CF2)x—CF2— with x≥6.
EP 1 396 572 A1 describes a method for producing an aramid fabric having a water-repellent finish, comprising the steps of                a) providing an aramid yarn,        b) applying a hydrophobic agent, preferably comprising fluorine and carbon atoms, onto the aramid yarn,                    wherein acrylate polymers with perfluoroalkyl groups having the structure CF3—(CF2)x—CF2— with x≥6 are particularly preferred,                        c) drying of the aramid yarn resulting from step b),        d) producing a woven fabric from the aramid yarn resulting from step c) and        e) thermally treating said woven fabric.        
Textile fabrics of aramid fibers provided with a finish comprising fluorine and carbon atoms, such as acrylate polymers with perfluoroalkyl groups having the structure CF3—(CF2)x—CF2— with x≥6, show a high water-repellent effect and thus the requested ballistic protective effect. However, due to ecological reasons, customers ask more and more often for finishes on textile fabrics of aramid fibers that do not contain any fluorine.
Therefore, it is an object of the present application to provide a textile fabric of aramid fibers wherein the finish does not contain any fluorine but is at least as water-repellent as known finishes comprising acrylate polymers with perfluoroalkyl groups having the structure CF3—(CF2)x—CF2— with x≥6, and wherein a textile fabric of aramid fibers finished with such a water-repellent finish exhibits at least the same antiballistic effect as a textile fabric of aramid fibers finished with the known finish of acrylate polymers with the perfluoroalkyl groups having the structure CF3—(CF2)x—CF2— with x≥6.